How do you find the magnitude <3.5, 12>? Precalculus Vectors in the Plane Vector Operations 1 Answer Ratnaker Mehta Jul 20, 2016 #||<3,5,12>||=sqrt178~=13.34#. Explanation: The magnitude of a vector #vecx=(x_1,x_2,x_3)# is denoted by #||vecx||# and is defined by, #||vecx||=sqrt(x_1^2+x_2^2+x_3^2)# Hence, #||<3,5,12>||=sqrt(9+25+144)=sqrt178~=13.34#. Answer link Related questions Question #b4ef9 What is meant by a component of a vector? How do I find the vertical component of a vector? How do i find the horizontal component of a vector? Is vector addition commutative? What happens when I multiply a vector by itself? What is the definition of vector addition? How do I do vector subtraction? What is a velocity vector? How can the law of cosines be used to find the magnitude of a resultant? See all questions in Vector Operations Impact of this question 1520 views around the world You can reuse this answer Creative Commons License